[ROVERNET - UK] 3500s head compatibility

[Robert Thornton]

Kent wrote : 
>>you are MUCH better off starting with a 3.5 block, either early or
late, than you would be investing in a factory 3.9, used or new. I will
never again buy a 3.9 for any reason. I would only buy a 4.0 if I knew
the vehicle and it's service history from new and intended to fit "top
hat" sleeves. <<

Hi Kent

What's the difference between investing in a new / used 3.9 or 4.0
block? They use the same bore, same liners. OK, the 4.0s are cross
bolted whereas the 3.9s are not, although they have provision for it and
the later interim 3.9 blocks have the longer crank to drive the oil
pump. But this does not influence the porosity issue.

Des Hammill seems to have scared a lot of people off 94 mm blocks.
There's been much debate about this on the Land Rover Owners forum
 
http://www.lro.com/nav?page=lroi.message.list&section=MESSAGE_READERS_FO
RUMS

Consensus of opinion, if I interpret it rightly, is that yes, a
significant number of 94 mm block do suffer this problem, particularly
if they are allowed to overheat. But a lot do not ever become porous,
and these may be in the majority. Some other manufacturer's alloy
engines can also have problems with heads / blocks cracking if they are
allowed to seriously overheat. 

Moral of the story seems to be keep your cooling system in top notch
order, regularly remove and clean out the cores of radiators and closely
monitor the operation of radiator hoses, thermostat, water pump and
cooling fan. In the case of P38 Range Rovers a complete re-think of
their cooling system is really warranted for all the reasons Hammill
identifies.

Rob